Matches in SemOpenAlex for { <https://semopenalex.org/work/W2022991643> ?p ?o ?g. }
Showing items 1 to 74 of
74
with 100 items per page.
- W2022991643 endingPage "100" @default.
- W2022991643 startingPage "92" @default.
- W2022991643 abstract "Aus dem leicht zugänglichen Tetrahydropyranyläther 1 des 21.21-Dimethoxy-pregnenolons wird durch Wittig-Reaktion nebst Hydrolyse 2, daraus durch Michael-Addition 3 und nach dessen Verseifung sowie Decarboxylierung 5 erhalten. Ringschluß des 5-acetats führt zu 7, aus dem durch Dehydrierung (Pd/Kohle) das α-Pyron 8 entsteht. – In Übertragung dieser Reaktionsfolge auf 3-Äthoxy-21.21-dimethoxy-20-oxo-pregnatrien (9) wird zwar in guten Ausbeuten das Enollacton 11 erhalten; nach dessen Dehydrierung gelang es aber nicht, das dünnschichtchromatographisch nachgewiesene 12 kristallin zu isolieren. Selektive Hydrierung von 11 führt glatt zur 5β-H-Verbindung 14, deren Dehydrierung mit Pd/Kohle 16 ebenfalls nur in geringer Ausbeute ergibt. Bei Versuchen, die Ketogruppe von 11 zur 3β-Hydroxy-Gruppe (nach Meerwein-Ponndorf oder nach Henbest) zu reduzieren, um danach in die Bufalin-Reihe zu gelangen, findet bevorzugt die Hydrierung des Enollacton-Rings unter Bildung von 15 statt. Preparations of Unsaturated Lactones of the Steroid Group, VI. Synthesis of Bufadienolides. I Starting from the readily accessible tetrahydropyranyl ether 1 of 21,21-dimethoxypregnenolone, 2 is obtained by Wittig reacton and subsequent hydrolysis. By Michael addition of 2 to 3, followed by saponification and decarboxylation, 5 is synthesized, whose acetate undergoes ring closure to 7. Dehydrogenation of 7 by means of Pd on carbon leads to the α-pyrone 8. – Using this reaction sequence for the synthesis of a bufaline compound from the pregnatriene derivative 9, the enol-lactone 11 is obtainable in good yields. After dehydrogenation of 11 it is not possible to isolate 12, detected by thin layer chromatography, in a crystalline form. By selective hydrogenation of 11 the 5β-H-compound 14 is obtained. Its dehydrogenation with palladium on carbon results only in a low yield of 16. Other dehydrogenation methods for reduction of the keto group of 11 to the 3β-hydroxy group (according to Meerwein-Ponndorf of Henbest) have been tried; however, hydrogenation of the enol-lactone ring to 15 preferably occurs." @default.
- W2022991643 created "2016-06-24" @default.
- W2022991643 creator A5020501298 @default.
- W2022991643 creator A5039821822 @default.
- W2022991643 creator A5039858789 @default.
- W2022991643 creator A5049549903 @default.
- W2022991643 creator A5091824048 @default.
- W2022991643 date "1970-11-30" @default.
- W2022991643 modified "2023-09-24" @default.
- W2022991643 title "Herstellung von ungesättigten Lactonen der Steroidreihe, VI. Synthese von Bufadienoliden, I" @default.
- W2022991643 cites W1990515304 @default.
- W2022991643 cites W2005725804 @default.
- W2022991643 cites W2020046541 @default.
- W2022991643 cites W2032414601 @default.
- W2022991643 cites W2051177640 @default.
- W2022991643 cites W2068685021 @default.
- W2022991643 cites W2086191277 @default.
- W2022991643 cites W2106992178 @default.
- W2022991643 cites W2151399563 @default.
- W2022991643 cites W2172164690 @default.
- W2022991643 cites W2316133658 @default.
- W2022991643 doi "https://doi.org/10.1002/jlac.19707410111" @default.
- W2022991643 hasPubMedId "https://pubmed.ncbi.nlm.nih.gov/5499842" @default.
- W2022991643 hasPublicationYear "1970" @default.
- W2022991643 type Work @default.
- W2022991643 sameAs 2022991643 @default.
- W2022991643 citedByCount "8" @default.
- W2022991643 countsByYear W20229916432020 @default.
- W2022991643 crossrefType "journal-article" @default.
- W2022991643 hasAuthorship W2022991643A5020501298 @default.
- W2022991643 hasAuthorship W2022991643A5039821822 @default.
- W2022991643 hasAuthorship W2022991643A5039858789 @default.
- W2022991643 hasAuthorship W2022991643A5049549903 @default.
- W2022991643 hasAuthorship W2022991643A5091824048 @default.
- W2022991643 hasConcept C119889771 @default.
- W2022991643 hasConcept C155647269 @default.
- W2022991643 hasConcept C161790260 @default.
- W2022991643 hasConcept C178790620 @default.
- W2022991643 hasConcept C185592680 @default.
- W2022991643 hasConcept C24292678 @default.
- W2022991643 hasConcept C2780595602 @default.
- W2022991643 hasConcept C71240020 @default.
- W2022991643 hasConcept C94412978 @default.
- W2022991643 hasConceptScore W2022991643C119889771 @default.
- W2022991643 hasConceptScore W2022991643C155647269 @default.
- W2022991643 hasConceptScore W2022991643C161790260 @default.
- W2022991643 hasConceptScore W2022991643C178790620 @default.
- W2022991643 hasConceptScore W2022991643C185592680 @default.
- W2022991643 hasConceptScore W2022991643C24292678 @default.
- W2022991643 hasConceptScore W2022991643C2780595602 @default.
- W2022991643 hasConceptScore W2022991643C71240020 @default.
- W2022991643 hasConceptScore W2022991643C94412978 @default.
- W2022991643 hasIssue "1" @default.
- W2022991643 hasLocation W20229916431 @default.
- W2022991643 hasLocation W20229916432 @default.
- W2022991643 hasOpenAccess W2022991643 @default.
- W2022991643 hasPrimaryLocation W20229916431 @default.
- W2022991643 hasRelatedWork W1491892276 @default.
- W2022991643 hasRelatedWork W1982728301 @default.
- W2022991643 hasRelatedWork W2060566628 @default.
- W2022991643 hasRelatedWork W2316065102 @default.
- W2022991643 hasRelatedWork W2405385153 @default.
- W2022991643 hasRelatedWork W2406910599 @default.
- W2022991643 hasRelatedWork W2950538501 @default.
- W2022991643 hasRelatedWork W2951533543 @default.
- W2022991643 hasRelatedWork W2997230349 @default.
- W2022991643 hasRelatedWork W3151588278 @default.
- W2022991643 hasVolume "741" @default.
- W2022991643 isParatext "false" @default.
- W2022991643 isRetracted "false" @default.
- W2022991643 magId "2022991643" @default.
- W2022991643 workType "article" @default.